Philippine President Rodrigo Duterte, saying he was "not a fan" of the United States, vowed Saturday to steer an independent course for the key Asian ally and refrain from confronting territorial rival China.

The incendiary leader made the comments after a controversial first foreign trip and spectacular falling out with US President Barack Obama, who he called a "son of a whore".

"I am not a fan of the Americans... Filipinos should be first before everybody else," Duterte told reporters upon arrival in his hometown of Davao city Saturday.

"In our relations to the world, the Philippines will pursue an independent foreign policy. I repeat: The Philippines will pursue an independent foreign policy."

The president's trip to a summit in Laos was overshadowed by his verbal tirade, which saw Obama cancel a planned meeting. The pair met briefly later after Duterte expressed regret.

The US, Manila's main military ally and the Philippines' colonial ruler until 1946, has criticised Duterte's brutal crackdown on crime, which has claimed 3,000 lives since he took office in July and drawn condemnation from the United Nations.

Obama has urged the Filipino leader to conduct his crime war "the right way" and protect human rights, but Duterte has dismissed it as being none of America's business.

The two also subtly differed on how to proceed after a UN-backed international tribunal in July outlawed most of China's claims to the strategic South China Sea, including areas that overlap with those of the Philippines and other neighbours.

Obama, whose government wants to ensure freedom of navigation in the waterway, brought up the contentious issue at the Laos forum also attended by China.

He stressed that the tribunal's ruling was "binding" and could not be ignored by Beijing, which has rejected it.

Duterte favours a "soft landing" for the issue and said Saturday it would be counter-productive for his militarily weak nation, which hosts small units of US forces, to confront China or undertake actions that could lead to armed conflict.

"I assured everybody that there are only two options there: We go to fight, which we cannot afford at all, or talk," he added.

On Friday during an overnight visit to Indonesia, Duterte announced China had pledged to help build drug rehabilitation centres to treat Filipino crystal meth users.

Law enforcement officials believe criminal gangs in China, Taiwan and Hong Kong supply most of the illegal and highly addictive stimulants to the Philippines.

"Only China has offered to help us," Duterte said Friday, according to an official transcript of a speech he gave to the Filipino community in Jakarta.